Columbia, Missouri. With a population of more than 100,000 this county seat is no rural backwater, but thanks largely to its location, out in the vastness of the American Midwest, its atmosphere is undeniably more "small town" than "big city".

The city is the scene of a notorious murder that took place in 2001, when a local sports journalist was savagely beaten and strangled to death in his newspaper's parking lot. It's here, at the Boone County Courthouse in 2005 - after a trial that has since been subject to national controversy, with both key witnesses having come forward to admit perjury - that Mr Ryan Ferguson was convicted of second-degree murder and sentenced to 40 years in jail; he was 19. And it's here that award-winning documentarian Mr Andrew Jenks has come, to see if he can shine a light on a case that is still provoking intense debate.

By getting really invested in
the stories, I almost do the opposite of drinking the Kool-Aid. I become, of whoever I'm following, their
harshest critic

As a film-maker, Mr Jenks started young. The son of Mr Bruce Jenks, a director at the United Nations Development Programme, he spent much of his youth abroad, visiting Brussels and Nepal as a child. "I'd always have this bulky VHS camera in my hand," he says. "Travelling around where there weren't many people speaking English, that camera became my best friend by default."

After a short stint at New York University, his career began in earnest at age 19 when he created Andrew Jenks, Room 335, a poignant look at end-of-life "assisted living" that saw him move into a nursing home for five weeks. Since then, his charismatic, disarming interview technique has helped make his fly-on-the-wall documentary series, World of Jenks, one of MTV's biggest shows. Sharing the screen with his young participants, Mr Jenks is very much the star of the show, as the name suggests. He insists that by stepping out from behind the camera and forming relationships with his subjects, he is able to offer a greater level of impartiality. "By getting really invested in the stories, I almost do the opposite of drinking the Kool-Aid," he explains. "I become, of whoever I'm following, their harshest critic." If that's true, he's sure to put an interesting spin on the story of Mr Ferguson, who has become something of a Columbia cause célèbre.

It's just really eerie; it's like a cloud that hangs over this place. People have been talking about it for 10 years

Mr Jenks may not have been here long, but the small-town vibe has already hit home. "Everybody knows about this case," he says of his first few days in the city, which have already seen him visit diners, barbershops and bowling alleys around the city. "It's just really eerie; it's like a cloud that hangs over this place. People have been talking about it for 10 years." But despite that duration, a sense of intrigue still pervades. "There are definitely people in the community who feel as if they have a good idea of who it is - if it's not Ryan. It's spooky."

The story of a famous journalist descending on a small town to cover a murder investigation is not a new one around these parts. It was in 1959, 500 miles out west of here, as the crow flies, in the town of Holcomb, Kansas, that Mr Truman Capote first covered events that would form the basis of his seminal work, In Cold Blood. His time in Holcomb was later depicted in the 2005 film, Capote. It's a comparison not lost on Mr Jenks, and one that was brought into sharp focus when MR PORTER came to town. "The dichotomy between documenting this case in a small city, and wearing these expensive - and what the locals saw as outlandish - clothes, was really interesting," he says. "It did remind me of Philip Seymour Hoffman in Capote, who came out west from this lavish, socialite lifestyle in New York City to become engaged in one person's story."

Unlike Mr Capote's venture into the Midwest - documented in such vivid detail in In Cold Blood - it remains to be seen how Mr Jenks' time in Columbia will play out. But for him, that uncertainty is all part of the process. "There's a chance that Ryan gets out of jail in the next few months; there's a chance that he never gets out. Working with something so real, the conclusion is never set."